Method of making cinematograph color-films.



1. E. THORNTON.

METHOD 0r MAKING CINEMATOGRAPH COLOR FILMS.

APPLICATION FILED JUNE 7. I913.

Patented Nbv. 6, 1917;

WETN ESSE$.

A BENT.

JOHN EDWARD THORNTON, OF ROCHESTER, NEW YORK, ASSIGNOR TO JOHN OW'DEN O'BRIEN. OF MANCHESTER, ENGLAND.

METHOD OF MAKING CINEMATOGRAPH COLOR-FILMS.

Specification of Letters Patent.

Patented Nov. 6, 1917.

Application filed June 7, 1913. Serial No. 772,440.

To all whom it may concern:

Be it known that I, JOHN EDWARD THORN- TON, a British subject, residing at Rochester, N. Y., United States of America, have invented certain new and useful Improvements in Methods of Making Cinematograph Color-Films, of which the following is a specification.

This invention relates to the production of two-color cinematograph film pictures or positives from a single-width two-color negative of the alternatingitype one color section picture being formed on the front and the other section picture of different color on the back of the film through the agency of some salt of silver, exposure to light eflect, and development.

It consists essentially in printing from a single alternating negative on one side andthen on the other side of a duplex film sensitized both back and front with a light-obstructing medium, between the sensitized layers and subsequently developing, washin and drying both prints.

he invention is an extension of that described in my application filed on the 10th April 1913, Serial No. 760200, in which differently colored section pictures are formed on the back and front of' the same piece of film stock, as a duplex film.

There is however an important difference between the two,in my application filed on the 10th April 1913, Serial No. 760200 two separate negatives are required-one for each color-and they are produced in a double camera, on a doube-width strip of negative film, and taken through two colorscreens, whereas in this application one neg ative only is required.

Moreover there is no existing business organization at the present time that uses double-width film for producing negatives, though there is no difiiculty in doing so, Whereas there are already several very large organizations in existence makingtwo-color negatives on the single-strip alternating system.

In producing cinematograph color prints according to this invention any printing process of the rapid class can be used, provided images in colors can be obtained either directly or indirectly; but processes of the slow class are not suitable on account of the long exposure required.

In the slow class would be included those based upon the use of bichromate, iron and similar slow-printing sensitive salts.

In the rapid class would be included all processes based upon the direct or indirect use of silver salts.

The following are examples of processes suitable for the second or rapid class.

( 1). Gelatino-silver-bromid' (or chlorid) or like emulsions such as now used for regular black and White prints. After the print has been exposed, developed, and washed it may be treated by any one of the following methods A. Its black images may be toned, one side to anorange-red, the other to a blue-green color.

B. The silver may be removed and replaced by dyes, by one of the well-known substitution? methods; or converted into a salt which re-acts as a mordant on dyes and precipitates them in situ.

C. The reduced-silver image may be rendered insoluble by treatment with bichromates; or with a mixture of potassium bichromate, ferricyanid, andbromid; or with potassium bichromate and cuprie bromid; then the silver bleached or removed; the unhardened gelatin dissolved and removed by hot water, leaving a hardened gelatin image in varying degrees of relief; and finally the duplex reliefs stained up by suitable dyesred on one side of the. film and green on the other.

Or, D. After hardening and bleaching the silver image as above, the unhardened parts may be dyed up, andthen mordanted.

(2). Combined silver-bromid and pigment, as typified by the so-called carbograph process, or a modification thereof which is rather more suitable for picture film images than the ordinary process. The image is printed, developed, and washed as usual; then bichromated and hardened; the silver bleached or else dissolved out; and the unhardened gelatin removed by hot water;

leaving a picture in colored pigment. Dye

tized film adapted to be printed from the negative shown in Fig. 1;

Fig. 3 is a perspective view of a finished v film, the pictures B shown thereon being ill) printed from .the alternating red colored picture sections B of the negative; and

Fig. 4: is a perspective view of the finished film showing the pictures A. printed from the alternating green picture sections A of the negative.

in the following description I will assume gelatino-silver-bromid is used and that the black images are afterward changed to red and green.

The film is coated or sensitized on both front and back faces, thus producing a du-- plex film, but between the central celluloid base I) and one of the sensitized layers a (or it may be both if preferred) a layer 0 of light-obstructing material, such as watersoluble dye in gelatin, is applied. The purpose of this is to prevent light penetrating to and impressing one film during printing of the other. This color washes out during development, fixing and washing as described in my application filed on the 10th April 1913, Serial No. 760200.

- The duplex film is then ready for printing, which'in this inventiona is carried out a little difierently from the method in universal use for all standard film, and requiring also a difierent arrangement of the printing machine feed devices. I

The regular type of intermittent printing machine is used, but its feed is so arranged that the printing negative is drawn forward two steps or two pictures for every one step or one picture that the sensitized film is drawn. The result is that section picture No. 1; of the negative is impressed upon the front face of the sensitive film, then Nos. 3, 5, '7, 9, and so on, these impressions A from the picture motions A of the negative which are, for example, blue green, succeeding each other in close order without blank spaces between.

The two films then before. developing,

washing and drying pass into a duplicate printing machine, which may he so coupled up to the first that the two are combined to form one co-acting piece of apparatus. Tn passing from one machine to the other the sensitive film turns over, so that its other sensitive side is presented to the printing negative, which however does not turn. The same procedure in printing is again repeated, but the section picture negatives Nos. 2, a, 6, 8, and so on are impressed this time, care being taken to see that No. 2B is superimposed upon No. l and that the regisintense rator; and still more so if the two-length negative record is drawn forward and periorated two pictures at a time, and the single length positive record one picture at a time.

The printed positive film after being printed on both sides is then developed, washed, dried, and finished ofi' with all section pictures on one side red and all on the other side green, or in colors which are substantially complementary. The spaces where no part of the image appears remain transparent and pass white light so that the resulting picture when projected on the screen is composed of white, red, green, and 4 suchother shades as are produced by over- 7 lapping of the red and green in parts.

To bring the two opposite section pictures in closer contact to one another a thinner celluloid stock may be used, which is afterward strengthened by applying an outer coating of celluloid, gelatin, cellulose. acetate, or other varnish to the back and front faces, which also serves as a protectionfto the printed images by completely inclosing and covering them.

What ll claim as my invention and desire to protect by Letters Patent is 1. The herein described method of producing two-color value positive pictures for cinematograph films, which comprises rinting two-color positive pictures of di erent color values in succession on a single strip of transparent film from a single; strip of negative film having the picture negatives of different color values arranged in alten nating sequence thereon, the alternating picture negatives of one col/0r value bein printed in direct sequence on'one side of the positive film and the pictures of the other color value being printed in direct. sequence on the opposite side of the positive film, the pictures on opposite sides'oi the positive film registering, and subsequently coloring the pictures onthe positive. film in the correct color.

2. The herein described method of pro-. ducing two-color value positive pictures for cinematograph films from a single strip of negative film having the picture negatives of difilerent color values arranged in alternating sequence thereon, which comprises ter is accurate, the pictures B produced in printing on one side of a transparent fi positive pictures from the picture negatives of one color value, and then printing in register on the opposite. side of the transparent fihn the positive pictures from the picture negatives of the other color value, the negative film and positive film being superposed (llll'll'1g S21l(l printing operations and the negative fihn being advanced twice the distance of the positive fihn between the 10 printing of each picture, and subsequently coloring the pictures on the positive film in the correct color.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

JOHN EDWARD THORNTON.

Witnesses H. W. WILsON, JOHN R. NESBETT. 

